Olefin Metathesis Reaction in Water and in Air Improved by Supramolecular Additives

Abstract

A range of water-immiscible commercially available Grubbs-type precatalysts can be used in ring-closing olefin metathesis reaction in high yields. The synthetic transformation is possible in pure water under ambient conditions. Sulfocalixarenes can help to boost the reactivity of the metathesis reaction by catalyst activation, improved mass transfer, and solubility of reactants in the aqueous reaction media. Additionally, the use of supramolecular additives allows lower catalyst loadings, but still high activity in pure water under aerobic conditions.

Pillar5arenes as Supramolecular Hosts in Aqueous Biphasic Rhodium‐Catalyzed Hydroformylation of Long Alkyl‐chain Alkenes

“…Subsequent reaction with methyl chloroacetate in acetonitrile in the presence of potassium carbonate at 80 8C for 48 h affords pillar5arenes randomly substituted by both methyl and methyl carboxymethyl groups (P5 A-(Me) 10-x -(CH 2 COOMe) x with x being the number of methyl carboxymethyl groups distributed on both sides of the macrocycle, compounds [8][9][10][11][12][13]. Further saponification of the ester functions under basic conditions (NaOH in water at 100 8C for 12 h) leads to the corresponding pillar5arenes featuring methyl and sodium carboxylmethyl groups randomly substituted onto the cyclic structure P5 A-(Me) 10-x -(CH 2 COONa) x (compounds [14][15][16][17][18][19].…”

“…P5 A-(Me) 10-x -(CH 2 COONa) x (14)(15)(16)(17)(18)(19) In a 100 mL round flask was prepared a saturated solution of NaOH (12 mL) in ethanol (40 mL). Compounds 8-13 (1.5 g) was then introduced and the mixture was heated to reflux and stirred for 15 h. The product was precipitated with aqueous hydrochloric acid (50 mL) and filtered to obtain P5 A-(Me) 10-x -(CH 2 COOH) x.…”

“…Once the catalytic process is complete, the product is release in the organic phase and another substrate molecule gets into the host cavity. The concept has been widely exploited with cyclodextrins, (CDs), calixarenes,, or cucurbiturils as supramolecular hosts in various organometallic reactions, such as hydroformylation, carbon‐carbon coupling, and cleavage of carbonates or urethanes (Tsuji‐Trost reaction), to name only a few. It occurred to us that pillararenes, that consist of hydroquinone moieties linked together by methylene groups (Figure ),, could also be good candidates to molecularly recognize organic substrates.…”

Microwave-mediated Newman–Kwart rearrangement in water

“…In recent studies we could show that supramolecular additives such as sulfocalix[n]arenes can efficiently increase the catalytic activity of Suzuki and metathesis reactions performed in pure water. 27,46 The ability to solubilize hydrophobic reactants and an improved mass transfer are characteristics, which make watersoluble calix[n]arenes valuable for reactions in aqueous media or neat water. This tempted us to investigate the inuence of macrocyclic additives on the NKR.…”

Nonaqueous and Aqueous Emulsion ROMP Reactions Induced by Environment-Friendly Latent Ruthenium Indenylidene Catalyst Bearing Morpholine Substituted Bidentate (N, O) Schiff Bases

“…[7] Concerning the beneficial aspects of aqueous media in catalytic reactions, several research groups have been focused on the development of olefin metathesis catalysts that can run in aqueous media. [8] Water-soluble ruthenium metathesis catalysts were developed by integrating water-soluble phosphine, N-heterocyclic carbene (NHC), alkylidene, and N-donor ligands in the overall structure. [9] Although these catalysts are efficient in olefin metathesis reactions of hydrophilic substrates in aqueous media, only a few of them have shown high efficiency in metathesis reactions.…”